Catalytic Abatement Of Typical VOCs Based On Industrial Sources In Hubei Province

Volatile organic compounds（VOCs）have toxic and irritating odors,which are not only highly toxic to animals,plants and the human body,but also cause serious and persistent pollution to the environment.Among VOCs treatment technologies,the catalytic combustion method has been successfully applied to the removal of VOCs in several industries due to its advantages of energy saving,high efficiency,environmental protection and easy control.Transition metal oxides have been widely studied as thermal oxidation catalysts for VOCs due to their lower cost and good activity.The various valences of MnO_x(Mn²⁺,Mn³⁺,Mn⁴⁺)make it have strong reducibility.At the same time,it is widely used in the catalytic combustion of VOCs because of its diverse crystal structure and morphology.δ-MnO₂ successfully synthesized by a redox method between KMnO₄ and butanol at room temperature.The catalytic performance for toluene were compare withε-MnO₂andγ-MnO₂ which were prepared by traditional methods.It was found thatδ-MnO₂ showed the best catalytic oxidation performance of toluene(T₁₀=160°C and T₉₀=199°C).Further research found thatδ-MnO₂ had larger BET specific surface area,stronger reducibility and more oxygen vacancies.It is well-known that the catalytic activity of a transition metal oxide is associated with these factors,soδ-MnO₂ has higher toluene catalytic activity.The smaller the space velocity,the stronger the apparent oxidation activity ofδ-MnO₂ to toluene.The lower the toluene concentration,the stronger the apparent oxidation activity ofδ-MnO₂ to toluene.The 12-hour stability test results show that within a certain period of time,theδ-MnO₂ catalyst will not show obvious deactivation,theδ-MnO₂ sample has good water resistance,and the deactivation due to water is reversible.The in-situ DRIFTS results indicate that the toluene oxidation overδ-MnO₂ occurs through the benzyl alcohol-benzoic acid-maleic anhydride-acetate pathway.δ-MnO₂ has the advantages of simple synthesis method,mild synthesis conditions,good catalytic activity and can be large-scale produced.Therefore,δ-MnO₂ sample is a potential catalyst in practical application for the catalytic combustion of toluene and other VOCs.